Thermal stability of the unstable fcc-Fe50Cu50 phase prepared by mechanical alloying

Abstract

An unstable fcc-Fe50Cu50 alloy has been prepared by milling of elemental powder blends. The structure and the decomposition behavior of the alloy were studied by x-ray diffraction and Mössbauer spectroscopy. A broad distribution of different local environments of the iron atoms was observed in the fcc-FeCu phase. This indicates that Fe and Cu are mixed on an atomic level. In the initial state of decomposition, iron atoms precipitated coherently in the fcc-FeCu matrix as fcc-Fe particles. At higher annealing temperatures the particle size increased during the thermal treatment, and the fcc-Fe precipitates transformed into the bcc-Fe structure.

Investigation of the chemical homogeneity of Cu80(Fe,Co)20 powders produced by mechanical milling

“…The spectra of the as-milled powders reveal the presence of a paramagnetic contribution, with hyperfine parameters (ı = 0.16 ± 0.02 mm/s, = 0.50 ± 0.02 mm/s) that correspond to Fe atoms in Cu [12,13]. As an example, in the spectrum of the sample milled for 3 h, both magnetic and paramagnetic contributions are observed (see Fig.…”

Quasicrystalline phase formation in the mechanically alloyed Al–Cu–Fe system

“…6 shows the Mössbauer spectra of the investigated samples and the corresponding p(B hf ) distributions. The spectrum of the as-milled alloy resembles an amorphouslike sextet and is related to a mechanically alloyed supersaturated Cu(Fe) solid solution with Fe content of about 50 at.% [49,50]. A small peak is observed in the p(B hf ) distribution at B hf y33 T, revealing the presence of a small amount of a-Fe (a weak sharp sextet in the spectrum), which becomes more evident under heating.…”

Structure and Magnetic Properties of Aerosol Nanoparticles of Fe and Its Alloys

“…In particular, the very fuzzy lines of sextet with the hyperfine field H i = 20.6 T were referred to the metastable fcc FeCu alloy and the paramagnetic singlet to the fcc Fe [112]. After high-temperature annealing the singlet remained, with the amount of the fcc Fe and of the bcc Fe increasing at the expense of the decrease of the fcc FeCu component.…”

“…This means that more than a half of the Fe atoms must have a copper atom at its first coordination sphere, which is not feasible because of the low solubility limit of copper in iron. In addition, the presence of many Cu atoms contributes to their association, thereby violating the basic assumption of independent random distribution of impurity atoms in the Fe lattice [5,112,119].…”